In the tire industry there are two basic systems that provide for under-inflated operation of a tire. The first system employs an insert set in the wheel rim that supports the underside of the tire tread when the tire is operated in an underinflated state; U.S. Pat. No. 5,785,781 discloses one such system. The second system employs a self-supporting tire wherein the tire sidewalls are reinforced such that during underinflated operating conditions, the tire is capable of supporting itself to permit operation; U.S. Pat. Nos. 4,365,659, 5,158,627, 5,368,082 and 6,453,961 disclose such self-supporting tires.
Each system has its limitations, making each system more suitable than the other system for particular applications. Systems using the wheel inserts can result in strike-through for low sidewall tires and smaller tires, as well as being more complex to assemble due to the wheel mounted support; while self-supporting tires for large sidewall tires and larger tires have a larger mass, leading to a decrease in rolling resistance and comfort.
The previous invention enables the two different solutions to cooperate to result in a simpler run-flat solution. The present invention is suitable for mid-size applications and combines the best features of both types of systems.